Our research is concerned with mechanisms of the regulation and control of wound healing. Understanding these mechanisms is of importance not only to basic biology but to those fields of clinical medicine concerned with cell growth and wound healing. We have isolated a growth factor which is a potent mitogen for corneal fibroblasts in tissue culture, in organ culture, and in living animals. The growth factor stimulates, in rabbit corneas in vivo and in organ culture, cell growth similar to that observed in healing corneal wounds. We have developed methods for evaluating the biological activities of this growth factor in three systems: tissue culture, organ culture, an living animals. Tissue culture methods afford a means for determining its mechanism of action and for evaluating potential co-factors such as corticosteroids, ascorbic acid, and insulin. Our organ culture method permits a study of the growth factor under completely controlled conditions in tissues which retain their normal morphological and tissue-to-tissue relationships with their potential interactions. The stimulation of cellular hypertrophy and cell division produced in vivo by the growth factor permits the development of animal models for evaluation of its effects in clinically oriented problems. Insofar as cataract extraction is one of the most frequently performed surgical procedures in this country, a usuable growth-promoting factor may have immense practical value. Furthermore, it may be useful in the repair of accidental as well as surgical wounds. Some of the most tragic accidental wounds are ocular injuries in children. In these patients the exuberance of the healing process is frequently more damaging to vision than the injury itself. Ability to inhibit an overactive healing response may result in more successful restoration of vision in these unfortunate children. In addition to influencing wound repair itself the growth factor may improve the viability of stored corneal donor material for corneal transplantation. Prolonged donor storage time may be a valuable off-shoot of this research.